Greenhouse shade advice needed.

[DirtyCoconuts]

Steve - you hit it on the head, I, and i assume others, always read and forget to take the context in on my initial read and sometimes , often, get the ultimate conclusions wrong as a result.


very important lesson although one not so easily learned

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Alan spoke to our club Sep 16. He still sells plants. I bought some. His Web site is gone. I didn't ask him about that.

[Roberta]

Plants with dark flowers can have red in the leaves even if they aren't at the "suntan" intensity - if there is lots of anthocyanin around, expressing it in the leaves is very common.

[K-Sci]

Originally Posted by Roberta

Plants with dark flowers can have red in the leaves even if they aren't at the "suntan" intensity - if there is lots of anthocyanin around, expressing it in the leaves is very common.

I agree with this. I have seen orchid leaves turn red or red-purple in response to high light levels in the red end of the spectrum, but not the blue. I base this conclusion on a high intensity LED plant light I've used for several years. It was sold for growing marijuana and has separate controls for the red and blue end of the spectrum, but it has way too much red. It turns the leaves of most of my orchids anything from slightly reddish to a very deep red or deep purple - but this only happens only when the red LEDs are turned on. And it does this without heating the leaves and at the relatively low levels of 2500fc, which is lower light than my greenhouse has been for most of this summer.This summer many of them have lost most of the red.

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In his book that I keep telling people to read Motes mentions that magnesium deficiency can cause red spotting and streaking in Vandas during cool weather. It can take many months of supplementation to remedy the situation. I haven't read enough to know whether it occurs in other genera.

[Roberta]

Depends on the parentage... the so-called "warmth tolerant" ones are more like "hot muggy nights" tolerant... don't need the diurnal change in the fall. (I have never met a Cymbidium, with exception of some high level Chinese species, that balked at triple-digit F temps) But the spike trigger for the "standard" Cyms is that big day-night differential that happens naturally the fall in coastal California - it's not just the cool nights, it's the combination of cool nights and warm days. The so-called "warmth tolerant" breeding introduces some of the more tropical species so that they are less picky about that diurnal temperature range to bloom.

[Ray]

I’m glad others picked up the red coloration not necessarily being due to deficiencies, but it can be. Leaves will tend to be dark, dull, and smaller in that case.

The business about phalaenopsis needing more nitrogen than other orchids is simply untrue. It is more correlated to growth rate than genus.

[Shadeflower]

I am already postivie I am seeing beneficial results after 2 days

Nah just joking but nothing has died yet so that's good.

Like ES says I just watched it recently in the motes video.

That is what my testing is for but it will take 6 months for me to have any conclusions.

I know all about the reddenning but why will some develop reddening and others not? We don't have the answer, that much I know. I can carry on assuming it is just what some do and others don't but that's not my style so just letting people know I will be testing the hypothesis to back off the light if leaves turn red or maybe investigate if it is because plants are trying to grow faster than the nutrients they are receiving.

I have been feeding most my orchids with just 10 ppm Magnesium this year, Roy Tokunaga recommends 20 ppm minimum.

So I'm in a perfect position to make these observations. I will show a picture of the red dendrobium leaf if I can.

[Roberta]

Thanks! Den brymerianaum didn't survive, alas.. I have heard from others that it is tricky. I tried a couple of times, bloomed once or twice so I got my pix, then lost. Den falcorostrum is easy where I live. Alas, international shipping/permits very nasty, though. The trick on that one seems to be chilly nights. Fred Clarke mentioned in one of his talks that he had it in the GH, it got very large but nary a flower... he finally got disgusted, told it sink or swim, put it outside, and it bloomed beautifully. So classic Aussie Den culture. I don't think it so much the "dry" (I don't bother to dry them out) but rather the cool nights.

All of the Mexican Laelias (still considered Laelia) like anceps, autumnalis, gouldiana have the potential to get fairly large. I love them because they are tough as nails - temperature range somewhere between -3 C and 40 C (28 deg F to over 100 deg F) and drought-tolerant. Of the Brazilian Laelias (now Cattleya) consider looking for L (C) jongheana - huge flowers for the size of the plant which is quite compact.. It's one of those where the buds emerge from the new leaves without going through the "sheath" stage. But what's not to love about a 6 inch (15 cm) flower on a plant that is the same height or maybe smaller.

In short, I mostly love the ones that I can grow outside (cold tolerant) - GH is tiny, stuffed, and not getting any bigger. In the yard, there's always room for one more... Cyms are the easiest of all where I live - one of the best climates in the world for Cyms. To the point that they don't get enough respect. Also very easy for me to get-several major Cym growers with nurseries within an hour or two drive, they often supply society raffle tables, auctions, etc.

I know that getting these plants in the UK has been somewhere between difficult and impossible. But shows are starting up in the next few months. (I subscribe to Orchid Review so I'm on the RHS email list and have seen notices for Chelsea Flower Show) International vendors from the EU and South America may not want to deal with small individual orders, but for shows they do large imports. I strongly suspect that they operate somewhat like they do in the US - when they come for a show, they will ship plants that are pre-ordered, once they get inside the country. Shadeflower, if you are not a member of the RHS you should be... Orchid Review is a terrific magazine, and also you'll find out about shows.

[isurus79]

I’ve never heard of increasing blooms with lower light and I’ve never heard of yellowing leaves occurring during flowering because the plant is sucking energy from the leaves and sending them to the blooms. I don’t think that’s how their biology works. Can you provide links for where you’re getting this information from?